1. Field of the Invention
The invention generally relates to electric baby food warmers and methods for heating baby food, and more specifically to an electric baby food warmer for heating baby food held in a container by means of a heat transfer medium. The baby food warmer comprises a bowl where the container can be inserted for heating, and an electric heating for heating the bowl bottom. The invention further relates to a cover for an electric baby food warmer and to a process for heating baby food held in a container.
2. Description of the Related Art
Presently, conventional baby food warmers are filled to the brim with approx. 150 ml of water. Such conventional baby food warmers are known, for example, from EP 0 696 428 B1 or U.S. Pat. No. 5,773,795. In these cases, a baby's feeder with baby food or a glass container with an instant meal is immersed into the water filling the container. The water filling the container is in direct contact with an electrically heated element and serves as heat transfer medium to the bottle and the food contained therein. That is, first, the water filling the container is heated, which in turn heats the container with the baby food. By means of a thermo regulator, the heating element is switched off as soon as the water filling the container has reached a predetermined adjustable temperature.
However, as the temperature of the water filling the container is in general higher than the desired temperature of the baby food if the food is to be heated quickly, even after the heating energy has been switched off, the temperature of the food further increases if the bottle remains in the baby food warmer. Therefore, with such conventional baby food warmers, there is a problem that, if a very fast heating is desired, a very high temperature of the water filling the container has to be adjusted and the heating process has to be interrupted by withdrawing the food container if the temperature of the water bath has reached a predetermined temperature. An all-automatic and fast heating of baby food is difficult with conventional baby food warmers.
From U.S. Pat. No. 6,234,165 B1, a method and a device for a portable baby food warmer independent of an electric energy supply are known, where heat is generated by an exothermic reaction which heats the baby bottle. This portable baby bottle heater which does not work with electric energy, however, has a drawback in that for its operation always chemicals to be especially provided for generating the. exothermic reaction have to be kept ready. Furthermore, the two reaction partners have to be stored separately until the exothermic reaction is to be effected. In U.S. Pat. No. 6,234,165 B1, the exothermic reaction is triggered by releasing an appropriate electrolyte solution, for example a saline solution, into a heating element, for example made of a magnesium-iron alloy or of calcium oxide. The hot gas resulting from this reaction conveys its thermal energy to the baby bottle to be heated as it flows by.
This baby food warmer, however, has several severe drawbacks. On the one hand, the chemicals suited for such an exothermic reaction are for the major part of them problematic as to the safety and in particular in connection with food. This is true for the storage and handling of the starting materials as well as for the later disposal of the end products. Thus, there can be an explosion hazard, for example, when hydrogen gas is formed by the exothermic reaction of a magnesium-iron alloy with an electrolyte solution. Calcium oxide (“unstaked lime”), however, represents a highly caustic compound. On the other hand, most of the resulting gases possess a comparatively low enthalpy of vaporization, so that the heat transfer properties to the bottle can be unsatisfactory.
However, water has an extremely high enthalpy of vaporization, so that the energy conveyed during condensation is very high. These facts are utilized for conventional appliances for sterilizing baby milk bottles according to EP 0 183 956 B1 or U.S. Pat. No. 4,716,278. With these appliances, the baby bottles to be sterilized are in a vapor-filled space hermetically sealed with respect to the surroundings and are heated to nearly 100° C. without any filling with the opening facing downwards. However, these sterilizers are not designed to be used as baby food warmers.